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3.5.7 Cryogenic
Operation
The Hall sensor excitation current causes some self-heating of the sensor. This self-
heating can prevent cryogenic systems from achieving very cold temperatures when
measuring field. The cryogenic operation setting solves this problem by reducing the
amount of excitation current flowing through the sensor. When cryogenic operation
is active, the self-heating of the sensor is reduced by a factor of 100. The drawback of
cryogenic operation is increased noise and reduced accuracy.
A snowflake icon appears at the top right of the screen during cryogenic operation.
The feature can be disabled on the Measurement Setup screen.
The sensitivity of the sensor changes slightly with temperature. Use manual tem-
perature compensation (section 3.5.6) when operating in a cryogenic environment.
3.5.8 Probe High-
Frequency Operation
When measuring AC fields with frequencies greater than a few thousand hertz, small
loop areas in the probe will generate inductive voltage much like a coil. As the fre-
quency of the field increases so does the inductive voltage. The F71/F41 teslameter
compensates for the inducted voltages by default using a digital low-pass filter. This
feature is enabled by default whenever a probe is connected. It can be disabled on the
Measurement Setup screen.
FIGURE 3-27
Cryogenic operation
FIGURE 3-28
Probe frequency compensation
